[系统运维]【Linux】UDP协议实现C/S模式

（一）实现流程

（二）代码实现

（1）服务器端

#include <stdio.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <string.h>
#include <unistd.h>
void udp_ser()
{
	int sockfd = socket(AF_INET, SOCK_DGRAM, 0);
	if (sockfd == -1)
	{
		perror("socket err");
		return;
	}

	struct sockaddr_in saddr, caddr;
	memset(&saddr, 0, sizeof(saddr));
	memset(&caddr, 0, sizeof(caddr));
	int len_saddr = sizeof(saddr);
	int len_caddr = sizeof(caddr);

	saddr.sin_family = AF_INET;
	saddr.sin_port = htons(8000);
	saddr.sin_addr.s_addr = inet_addr("127.0.0.1");
	int ret = bind(sockfd, (struct sockaddr*)&saddr, len_saddr);
	if(ret == -1)
	{
		perror("bind err");
		return;
	}
	while (1)
	{
		char buff[128] = {0};
		//接受数据
		ret = recvfrom(sockfd, buff, 127, 0, (struct sockaddr *)&caddr, &len_caddr);
		if (ret == -1)
		{
			printf("ip = %s, port = %d已退出\n", inet_ntoa(caddr.sin_addr), ntohs(caddr.sin_port));
			break;
		}
		printf("ip = %s, port = %d, msg:%s\n", inet_ntoa(caddr.sin_addr), ntohs(caddr.sin_port), buff);

		//回复客户端
		sendto(sockfd, "ok", 2, 0, (struct sockaddr *)&caddr, len_caddr);
	}
	close(sockfd);
}

int main()
{
	udp_ser();
	return 0;
}

（2）客户端

#include <stdio.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <string.h>
#include <unistd.h>

void udp_cli()
{
	int sockfd = socket(AF_INET, SOCK_DGRAM, 0);
	if(sockfd == -1)
	{
		perror("socket err");
		return;
	}

	struct sockaddr_in saddr, caddr;
	memset(&saddr, 0, sizeof(saddr));
	memset(&caddr, 0, sizeof(caddr));

	int len_saddr = sizeof(saddr);
	int len_caddr = sizeof(caddr);

	saddr.sin_family = AF_INET;
	saddr.sin_port = htons(8000);
	saddr.sin_addr.s_addr = inet_addr("127.0.0.1");

	while(1)
	{
		printf("input: ");
		fflush(stdout);
		
		char buff[128] = {0};
		fgets(buff, 127, stdin);

		if(strncmp(buff, "end", 3) == 0)
		{
			break;
		}

		sendto(sockfd, buff, strlen(buff), 0, (struct sockaddr*)&saddr, len_saddr);

		memset(buff, 0, 128);
		int ret = recvfrom(sockfd, buff, 127, 0, (struct sockaddr*)&caddr, &len_caddr);
		if(ret <= 0)
		{
			perror("ser exit");
			break;
		}

		printf("ser: %s\n", buff);
	}

	close(sockfd);
}

int main()
{
	udp_cli();
	return 0;
}

（3）测试结果